A high pressure pump of the type described herein is shown in German OS No. 30 18 650 in which a bypass channel of a regulating bypass is disposed at about a right angle to a longitudinal inlet channel leading to the suction side of a vane pump. The bypass channel is closed by a flat face of a screw plug held flush with the longitudinal channel. As a result, favorable flow conditions are effected in the change of flow direction so that the partial flow regulated by the bypass valve has an improved feed to the suction side or to the inlet passage of the pump. The improved effect is due to the fact that the inlet oil flowing in from a feed passage connected to a tank is entrained by the partial bypass flow from the bypass valve under more or less high pressure.